The present invention relates to a liquid sample automatic analyzer for dipping a test strip in a liquid sample, such as urine and blood, to develop a color reaction for analysis of the sample.
Biochemistry components such as protein, glucose, ketone and occult blood in urine or pH of the urine, etc. are importantly concerned with health of human bodies, and are essential items to be measured in clinical examination. Methods of analyzing those items are divided into an quantitative analysis using reagents added to liquid sample in test tubes to develop reactions therein, and a semi-quantitative analysis using color reaction test strips. The latter analyzing method has been widely used in screening test for a group examination or diagnosis of diseases, because analysis results on many items can be readily and quickly obtained. The test strip consists of a plastic strip and reagent layers adhered to the plastic strip. The reagent layers are felts impregnate with reagent. The test strip is dipped into the urine in the test tube, being lifted from the test tube. The color tones of the reagent layers are observed by an operator to analyze the liquid sample when a predetermined time elapsed after the test strip was lifted from the test tube.
Urine examination using such color reaction test strips is primarily performed by operators visually checking the developed color tones. Recently, however, a demand for automatic urine analysis and hence a need for automatic analyzers in which all analyzing steps are automated have been increased for the reasons of an increase in the number of samples to be examined in examination rooms, a short of hands, and reluctance to those works handling urine. Adopting those automatic analyzers is effective in accurately controlling the time required to keep the test strips dipping in urine and controlling the elapse time required from lifting of test strips to measuring of the test strip. Further, the automatic analyzer can prevent errors due to individual differences in determining coloration of the test strip. Therefore, reliability of the examined results can be improved. There is thus a tendency that the automatic analyzers will be more and more widespread in future.
At present, liquid sample automatic analyzers are divided into two types; i.e., the dipping type that a test strip is inserted and dipped into a sample liquid in a sample container, and the pipetting type that a sample is sucked by a nozzle and discharged in a predetermined amount onto reagent layers on the surface of a test strip to be checked. The pipetting type analyzer has disadvantages of requiring a pump adapted to pipet the sample liquid and increasing the analyzer size. Another disadvantage of the pipetting type analyzer is that because measurement accuracy would be affected if the surplus sample is left on the test strip after dropping the sample and making it permeate into the test strip. Therefore, an additional work of removing the surplus sample is required, which renders the analyzing operation more complicated. On the other hand, the dipping type analyzer in which a test strip is dipped into a sample liquid is automated directly following the analyzing steps which are manually carried out in usual cases. This enables measurement to be performed with simple mechanisms and good reproducibility.
As one example of analyzers for automatically dipping test strips into sample liquids, an automatic analyzer is disclosed in JP, A, 61-91571 (JP, B, 4-26434).
The automatic analyzer disclosed in JP, A, 61-91571 comprises a test strip automatic supply mechanism including presence/absence and upper/lower surface detecting means, a sample container supply mechanism for automatically supplying sample containers in which liquid samples are contained, a liquid level detecting mechanism for detecting a liquid level in each sample container and, by way of example, informing a shortage of the liquid to be examined, and a photometric mechanism for making photometry on the test strips having been dipped in the samples. The disclosed automatic analyzer also comprises a test strip automatic handling mechanism for taking out each test strip from the test strip automatic supply mechanism, dipping it into the sample liquid in the sample container, and moving the test strip to the photometric mechanism after the dipping, and a control unit for controlling the operation of the test strip automatic supply mechanism and so forth.
By using the disclosed liquid sample automatic analyzer, labor imposed on the operators is reduced and reproducibility of measurement is improved.